<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="https://cdn.jsdelivr.net/npm/vue"></script>
</head>

<body>
<div id="app">

    <div v-if="showFlag" style="height: 200px;width: 100%;background-color: salmon"></div>
</div>

<script>
    var v = new Vue({
        el: '#app',
        data: {
            showFlag:true
        }
    })

    setTimeout(function () {
        v.showFlag = false;
    },1000)
</script>

</body>
</html>